As described in ELY-1541, obtaining GSSCredential using local-kerberos is redundant.
If not credential is provided, GSS based authentication mechanims will obtain it hiself.

When credential is not provided, kerberos-based mechanism will obtain appropriate GSSCredential from ccache himself.

Note on both, Oracle [1] and IBM JDK [2] can be path to the ccache defined using KRB5CCNAME environment variable - no need to set any JAAS login options for obtaining.

[1] https://bugs.openjdk.java.net/browse/JDK-6832353
[2] https://www.ibm.com/support/knowledgecenter/en/SSYKE2_9.0.0/com.ibm.java.multiplatform.90.doc/user/compsec_jgss_kerberos.html